The invention relates to a multi-standard display device for displaying pictures having a television-standard-dependent format, which device comprises a matrix display screen (such as a liquid-crystal display), a video signal processing circuit for receiving and processing the pictures, said pictures having a format-associated number of lines in a first direction, a sync separator for determining horizontal and vertical synchronizing signals and a standard-conversion circuit for converting the pictures of the television-standard-dependent format into pictures having a display screen-associated format.
A multi-standard display device of this type is known from European Patent Application EP-A-400286. A multi-standard display device is understood to mean a display device which is suitable for a plurality of television standards (PAL, NTSC, HDTV, etc.). Since a display device with a liquid crystal display screen (LCD) has a fixed number of display lines, the incoming video signal will have to be converted to a picture having a fixed number of display lines (viz. the number of display lines of the LCD screen) so as to ensure that the display device is suitable for, for example, both PAL (625 lines) and NTSC (525 lines).
In this known display device the lines which are absent (due to interlacing) are firstly inserted by means of interpolation after the incoming video signal has been stored line by line in the memory, and subsequently a vertical interpolation is performed, if necessary, in order to obtain the required number of lines (of the display screen).
A drawback of this known multi-standard display device is that the vertical interpolation is complicated and hence costly. Each pixel of each interpositioned line must be computed.